1. Field of the Invention
The present invention relates to a filter apparatus, which is to be used in combination with a canister for removing toxic substances from a vaporous fuel generated in a fuel tank or the like for an internal combustion engine.
2. Description of the Related Art
A vaporous fuel generated in a fuel tank mounted on a vehicle contains substances, which is harmful to an environment. Such a vaporous fuel should therefore not be discharged into the atmosphere without being subjected to a specific treatment. There has conventionally been taken a countermeasure of provision of a canister receiving adsorbent such as an activated carbon or the like and connected to a generation route of the vaporous fuel so as to remove the toxic substances from the vaporous fuel by means of the canister to obtain a clean air and then to discharge the thus obtained clean air into the atmosphere.
The vaporous fuel is not always introduced into the above-mentioned canister. When the pressure of the fuel tank becomes for example negative, the canister sucks in air. The sucked air and substances adsorbed by the adsorbent are mixed and then returned to a fuel system. When the air sucked by the canister contains foreign matters, the foreign matters may be accumulated in the canister, thus deteriorating its performance. In view of these problems, a filter apparatus is connected to the outlet portion of the canister, which communicates with the atmosphere.
As the filter apparatus for a canister, there has conventionally been used a filter apparatus as shown in FIG. 8. The filter apparatus 1 is provided with a housing 2 made of synthetic resin, a filter element 3 received in the housing 2 and a one-way valve 4 for opening or closing a passage, which can bypass the filter element 3. Air discharged from the canister (not shown) is introduced into a connection-opening portion 2a of the housing 2. Fluid introduced into the connection opening portion 2a opens the one-way valve 4 to enter a valve chamber 2b. The fluid in the valve chamber 2b is then discharged through an element chamber 2d and an atmospheric release-opening portion 2e into the atmosphere. When the pressure at the side of the canister becomes negative, air is sucked from the atmospheric release-opening portion 2e of the housing 2 into the element chamber 2d. The thus sucked air is filtered through the filter element 3 and then introduced into the canister through the connection-opening portion 2a. 
According to the above-described filter apparatus 1, the air discharged from the canister bypasses the filter element 3 and discharges into the atmosphere, thus leading to the maintenance of a small exhaust resistance. The air sucked into the canister is securely filtered through the filter element 3 on the other hand.
However, in the conventional filter apparatus 1 described above, the passage for discharging the fluid supplied from the canister and the passage for the air filtered through the filter element 3 are separated from each other at the region of the connection opening portion 2a. Such a structure requires the other valve chamber 2b provided other than the element chamber 2d, resulting in a complicated structure of the housing 2 and leading to increase in number of components. As a result, there take place an unavoidable increase in time and effort spent on manufacturing processes and assembling processes of the apparatus as well as an unavoidable increase in manufacturing costs due to the former.
An object of the present invention is therefore to provide a filter apparatus for a canister, which makes it possible to simplify the structure so as to decrease the number of components.
The present invention will be described below. Reference numerals appearing in the accompanying drawings will be given to the following description with parentheses for facilitating the understanding of the present invention. The present invention is not however limited only to embodiments illustrated in the drawings.
The aforementioned object can be attained by a filter apparatus (20A, 20B, 40A, 40B) for a canister of the present invention which is to be connected to an outlet portion (17c) of the canister (12) mounted on a fuel supply system (10) for a vehicle and comprises:
a housing (21, 41) having a connection opening portion (25, 45), which is to be connected to said outlet portion and an atmospheric release opening portion (26, 46) communicating with an atmosphere;
a filter element (30, 50) received in said housing;
wherein:
said filter element is provided with a filter body (31, 51) having a filtering function and with a partition (32, 52), which divides, in cooperation with said filter body, an inside of said housing into a clean-side zone (S1) communicating with said connection opening portion and a dirty-side zone (S2) communicating with said atmospheric release opening portion; and
said partition is provided with a one-way valve (33, 53), which permits fluid to pass from said clean-side zone to said dirty-side zone and prevents said fluid from passing from said dirty-side zone to said clean-side zone.
According to the present invention, the one-way valve (33, 53) is mounted on the filter element (30, 50), and it is accordingly unnecessary to provide the inside of the housing with any chamber for the one-way valve other than a filter element-receiving chamber. As a result, the shape of the housing can be simplified so as to decrease in number of components. It is therefore possible to decrease time and effort spent on manufacturing processes and assembling processes of the apparatus and reduce the manufacturing cost.
In the filter apparatus, the filter body may be formed into a hollow cylindrical shape or a flat plate shape. When the filter body having the hollow cylindrical shape is used, there may be adopted a structure in which one end of the filter body is joined to an inner wall of the housing so that a hollow portion (31a) of the filter body is connected to the connection opening portion (25) from the inside of the housing (21); the partition (32) is disposed at a side of the other end of the filter body; and there is provided the one-way valve (33), which permits the fluid introduced to a side of the other end of the hollow portion to pass therethrough and prevents the fluid from flowing into the hollow portion. When the filter body having the flat plate shape is used, there may be adopted a structure in which the partition is joined to the filter body so as to surround the outer periphery of the filter body; and the partition is joined over its entire periphery to the inner wall of the housing.
The aforementioned object can also be attained by a filter apparatus (20A, 20B) for a canister of the present invention which is to be connected to an outlet portion (17c) of the canister (12) mounted on a fuel supply system (10) for a vehicle and comprises:
a housing (21) having a connection opening portion (25), which is to be connected to said outlet portion and an atmospheric release opening portion (26) communicating with an atmosphere;
a filter element (30) received in said housing so that a hollow portion (31a) passing through a center of a filter body (31) of said filter element is connected to said connection opening portion from the inside of said housing at one end of said hollow portion;
wherein:
said hollow portion of said filter element is utilized as a part of a passage for introducing fluid, which has been introduced from said canister into said connection opening portion, into said atmospheric release opening portion; and
there is provided at an other end of said hollow portion a one-way valve (33), which permits the fluid to discharge from a side of said other end of said hollow portion and prevents the fluid from flowing from the side of said other end into said hollow portion.
According to the present invention, the fluid discharged from the canister (12) is introduced through the hollow portion (31a) of the filter element into the atmospheric release opening portion (26), and it is accordingly unnecessary to separate, at the connection opening portion (25), the passage for the fluid discharged from the canister and the passage for the air, which has been filtered by means of the filter element from each other. The one-way valve (33) can be provided at the other end of the hollow portion of the filter element, with the result that the filter element and the one-way valve can be received in the common chamber in the housing (21). The shape of the housing of the filter apparatus (20A, 20B) can accordingly be simplified so as to decrease in number of components. It is therefore possible to decrease time and effort spent on manufacturing processes and assembling processes of the apparatus and reduce the manufacturing cost.
In another embodiment, of the filter apparatus, there may be adopted a structure in which an end plate (32) is secured to the end of the filter body (31) of the filter element (30) and the one-way valve (33) is secured to the end plate. In this case, with respect to the shape of the housing (21), a simple vessel, which can receive the filter element (30) suffices.
The one-way valve (33) may have a structure in which the one-way valve can come into close contact with a valve seat (32b) by its own weight to close the hollow portion (31a) or can be apart from the valve seat under a function of pressure of the fluid introduced into the hollow portion. In this case, the pressure of the fluid introduced from the canister (12) into the hollow portion (31a) of the filter element (30) causes the one-way valve (33) to open, thus making it possible to discharge the fluid so as to bypass the filter body (31). In case that the suction of air takes place in the canister, the pressure of the hollow portion of the filter element becomes negative so that the one-way valve comes into close contact with the value seat (32b). Utilization of the negative pressure applied to the hollow portion of the filter element causes the one-way valve to close, and no power is therefore required for operating the one-way valve, thus obtaining the more simplified structure of the filter apparatus (20A, 20B). The negative pressure applied to the hollow portion becomes larger, according as airflow resistance in the filter body increases after a lapse of time. It is therefore possible to securely close the one-way valve when introducing the air into the side of the canister.
The aforementioned object can also be attained by a filter apparatus (40a, 40b) for a canister of the present invention which is to be connected to an outlet portion (17c) of the canister (12) mounted on a fuel supply system (10) for a vehicle, comprises:
a housing (41) having a connection opening portion (45), which is to be connected to said outlet portion and an atmospheric release opening portion (46) communicating with an atmosphere;
a filter element (50) received in said housing;
wherein:
said filter element is provided with a filter body (51), which has a filtering function and a flat plate shape and with a partition (52) connected to said filter body so as to surround said filter body;
said partition is joined over its entire periphery to an inner wall of said housing so as to divide an inside of said housing into a clean-side zone (S1) communicating with said connection opening portion and a dirty-side zone (S2) communicating with said atmospheric release opening portion; and
said partition is provided with a one-way valve (53), which permits fluid to pass from said clean-side zone to said dirty-side zone and prevents said fluid from passing from said dirty-side zone to said clean-side zone.
In this embodiment, the filter element (50) is provided with the one-way valve (53), and the shape of the housing can accordingly be simplified so as to decrease in number of components. It is therefore possible to decrease time and effort spent on manufacturing processes and assembling processes of the apparatus and reduce the manufacturing cost. The filter body (51) formed into a flat plate shape permits to decrease the height of the housing in the thickness direction (i.e., in the vertical direction of FIG. 5) of the filter body (51).
In the filter apparatus there may be adopted a structure in which the partition (52) is provided with a tubular member (52c), which connects the clean-side zone (S1) with the dirty-side zone (S2);
the tubular member is provided on its forward end portion with a valve seat (52d), which extends in a vertical direction when the filter apparatus is kept in its used condition; and
the one-way valve (53) has a structure in which the one-way valve can come into close contact with the valve seat by its own weight to close the tubular member or can be apart from the valve seat under a function of pressure of the fluid introduced from the connection opening portion into the clean-side zone.
In this case, no power is required for operating the one-way valve (53) thus obtaining the more simplified structure of the filter apparatus (40A, 40B). The negative pressure applied to the hollow portion becomes larger, according as airflow resistance in the filter body increases after a lapse of time. It is possible to securely close the one-way valve when introducing the air into the side of the canister. The negative pressure applied to the hollow portion becomes larger, according as airflow resistance in the filter body increases after a lapse of time. It is possible to securely close the one-way valve when introducing the air into the side of the canister.